The present invention is based on the invention disclosed in U.S. Pat. No. 3,876,846 and assigned to the assignee of the present invention and is particularly directed to an improvement therein which eliminates any flexible connections of any kind in the grounding switch and thereby increases the life span operating characteristics and reliability of the switch.
In metal enclosed pressurized gas insulated high voltage switchgear of the type described in U.S. Pats. Nos. 3,546,356; 3,573,342 and 3,643,003 all of which have been assigned to the assignee of the present invention it is conventional that the high voltage conductors be completely enclosed in grounded metal housings or covers at all points along the system. The advantage of this construction in both safety and reliability are obvious.
There is however one decided disadvantage in that it is not convenient to gain access to the high voltage conductor for low voltage tests commonly performed on a routine basis such as for example resistance tests on circuit breaker contacts, power factor tests on transformer insulation and other test operations.
Since it is desirable and even necessary periodically to measure the contact resistance of circuit breakers by the application of a known measured current across two terminals of the circuit breaker for the purpose of mearsuring the voltage drop between the terminals, it is conventional in outdoor substation design that this can be readily accomplished by clipping the test leads onto the exposed high voltage conductors at the upper ends of their bushings. However this is not possible in metal enclosed pressurized systems since the high voltage conductors are not exposed at any point along the system.